According to a calculation 13 of a peak operating rate of an air conditioner 19 based on an actual quantity of electric power used, a calculation 14 of an hourly average operating rate according to the peak operating rate in consideration of an outside air temperature, a calculation 15 of an hourly average surplus rate according to (1−average operating rate), and a calculation 16 of a control rate having the upper limit of the average surplus rate as a predetermined value, energy-saving control 17 of the air conditioner 19 is performed by a quantity of the control rate. Thereby, providing an air-conditioning control system 100 for achieving appropriate energy saving with simplified calculations.